Over the years there have been a number of proposals for turbine driven torpedoes. Initially, many of the proposals were for so-called open cycle Rankine system propulsion systems wherein a chemical reaction generated heat for vaporizing a working fluid which was employed to drive a turbine. Spent working fluid exiting the turbine was dumped overboard. While this approached adequately propelled the torpedo, it had a number of drawbacks. For one, if the working fluid did not totally condense immediately upon exiting the torpedo, or if it contained non-condensibles such as entrained air from the interior of the torpedo, it would leave a trail of bubbles allowing the torpedo to be detected.
In addition, the discharge of a gaseous fluid into water in which the torpedo was moving would likewise generate noise which could in turn result in detection of the torpedo.
Still another obstacle to the success of such proposals was due to the fact that the efficiency of the propulsion system was depth sensitive. Depending upon the depth at which the torpedo was running, the discharge of spent working fluid was against a greater or lesser head thereby raising or lowering the pressure differential across the turbine. This, needless to say, clearly affected turbine output and the running ability of the torpedo.
To avoid these and other problems, closed cycle systems were proposed. In closed cycle systems, the spent working fluid exiting the turbine was condensed in a so-called hull condenser and returned to the boiler or the like by means of a pump to be revaporized and again fed to the turbine for propulsion purposes. This approach eliminated or minimized a number of the difficulties mentioned previously that beset open cycle torpedoes. However, the development was not without a few drawbacks of its own. For example, a closed cycle system requires a so-called hull condenser in order to condense the spent working fluid. Desirably, such a system will additionally include a regenerator interposed between the turbine outlet and the hull condenser for the purpose of transferring residual heat in the spent working fluid to incoming liquid prior to its admission to the boiler to preheat the same to thereby maximize efficiency of the system.
Needless to say, the addition of a hull condenser and a regenerator as well as recycling plumbing and a pump increase the size and weight of the torpedo. This in turn has necessitated considerable expenditure of design effort to reduce the size of the various components of the system to allow a closed cycle torpedo to occupy a minimum of volume and with a minimum of weight. In order to accomplish the size reduction, however, flow paths for the working fluid are necessarily brought closer to the hull and may include abrupt changes of direction, both factors being conducive to the generation of noise within the torpedo hull, which noise may enable undesirable detection of the torpedo.
The present invention is directed to overcoming one or more of the above problems.